Florida Green Roofs and Insulation Value

 Do Florida Green Roofs provide insulation or not?  Good question.  There are several different perspectives on the topic.

One current belief is that green roofs may moderate roof temperature fluctuations, leveling out daily swings with respect to heat and cold.

Some of the data we have accumulated points to green roof soil media acting as a heat sink unless the soil is completely covered with shade from plants.


We've compiled data over the last year on how an Extensive Vegetated Roof absorbed and released solar energy (heat) over a twenty four hour cycle.

The roof under study is not insulated.  It has a tongue and groove pine deck with asphalt roll paper and asphalt shingles.  The interior was non-temperature (no heat or HVAC) controlled during the study periods.

The temperature measuring points were the exposed roof tongue and groove decking surfaces and consisted of multiple point averages.  Readings were taken with an EXTECH IR AN200 Unit.

The following illustrations depict a trend we've seen over and over.

The extensive vegetated roof systems absorb solar heat slower than asphalt roofing.  The extensive vegetated roof systems also retain the heat longer and then release the absorbed solar heat slower than asphalt roofing.

The linear trendlines for the temperature curves tell an important story also.  The ambient air temperature and the decking under the non-insulated asphalt shingle roof temperature possess more significant vertical trendline movements.

The temperature swings of the decking under the green roof are much more linear - showing a narrower range in temperature swings.

The data shown here is representative of spring, summer, autumn and winter with summer and winter having the more pronounced curves.

Importantly, we believe extensive green roofs, such as the one we are studying in this case, moderate temperature swings.

The data also points to the fact that green roofs serve as a heat sink, slowly absorbing solar heat during the daylight hours then slowly releasing the heat during the evening dark periods.

During the winter, green roofs may help by moderating cold temperatures at night by releasing heat back into the structure.  However if insulation separated the green roof from the structure then little or no heat would be recaptured unless a heat capture coil or other mechanism existed.

The inverse holds true for the summer.  During the day the green roof would moderate the solar heat gain to the structure by intercepting the solar radiation and absorbing it.  However at night, the green roof would radiate heat back into the structure, slowing the cooling process.

Again, if the roofs are insulated from the green roofs then there is no real benefit from a linear trendline perspective of sink and release.

We believe maybe this data points to the need for a method of harvesting the solar heat captured in the green roof during the day.  Potential capture processes could include water or silicon filled coils or tubes interwoven into the vegetated roof or other similar mechanical systems.

Harvesting the absorbed heat would allow for a more managed use of the solar heat resource.

We do believe that the notion of green roofs working to cool buildings should be more appropriately described as a moderating effect of absorption and slow release of solar heat.

Check out the range bars on the temperature curve chart to the left.

The green roof decking temperature has a much narrower temperature range.

Data points to the fact that green roofs absorb heat and quite a bit of it.

We always welcome your comments - feel free to email us anytime here.

Green roofs offer the potential to collect and harvest solar energy.  They may not be the cooling system we sometimes represent them to be.

A DIY, Low Cost $300 House with Plant, Water, Food & Commerce Integration

DIY Low Cost Housing Integrated with Plants, Water Collection and Chickens

We were asked to create a DIY, low cost residence that would cost less than $300.  My final design for the $300 home is based on years of work in developing a low cost, lightweight and affordable living roof and wall system to feed the Urban Core, clean stormwater and restore biodiversity to the cities.

800 SF DIY Low Cost Plant/Water/Food/Commerce Integrated Home

The end result is a place one can be proud of, 75 square meters overall in total, about 800 SF.  

Cost Breakdown

The front living area is approximately 500 sf, the greenhouse/shower area is 200 sf and the poultry house is 100sf.

Overhead Three Room View

The frame contains 4 sections of 2 fencing pipe placed 12 in the ground with a small amount of concrete. 1 electrical conduit is placed in the top open end of the pipe and bent in an arch until the opposite end slides into the opposing anchor pipe.  

Integration of Food Production Into the Home

Once the arches are up, galvanized fencing is attached to the frame creating a skin covering.  

Energy Efficiency of the $300 House

The roof is covered with a heavy duty tarp that can be rolled up for ventilation. 

Water Reuse Component of the $300 House

The living area, greenhouse and poultry house are separated by walls with a fencing skin also.

Front View of $300 House

Rainwater is collected in a gutter that runs along a knee-wall and stored in an underground cistern.  Water is pumped via hand pump to a solar shower bag that feeds the sink also. 

Greenhouse, Bath & Coop Placement

Drain water flows to irrigate the plants in the greenhouse and then water the poultry.

$300 House Integrated with Plants, Water & Food for Shelter, Commerce and Community

Living roofs and living permaculture walls line both sides of the home, creating privacy and delivering much needed food.  The green roofs are soilless and based on an extreme lightweight design (see photos).

Note:  My email is now kssonger@gmail.com.  The old address kevin@metroverde no longer exists.